Modular Network: As used herein, connotes a concentrated set of cooperating computers; typically, a set housed within a small box, and having modular form and functionality. The modular form allows for simple addition of computers to or replacement of computers in the set. Modular functionality allows for such computers to be designed for different functions despite their interchangeability (e.g. for one computer to function most efficiently as a personal computer and another computer to function most effectively as a network server). Such networks are further characterized in that they exhibit some or all of the following attributes: a) they contain a host computer and several client computers; b) the host computer, storage resources shared by it and the client computers, and a system bus linking the computers, are mounted on an integrated circuit board or substrate; c) the client computers are contained on cards which plug into sockets extending from the board/substrate; d) due to its short length, the system bus can be operated at a speed sufficient to allow for efficient operation of the client computers using data and programs accessible to these computers primarily through that bus; e) operation of the host computer subsystem as a network server relative to a network external to the respective set; f) operation of the client computer cards as both masters and slaves of the system bus; and g) operation of the system bus with a plurality of different signaling protocols, including a network signaling protocol by means of which the host and client computers are linked into a data communication network confined to the bus and its connections, this network serving to allow the client computers to exchange large data packets (e.g. packets larger than the amount of data transferrable on the bus in a single cycle of bus operation) both with each other, as peers, and with the host subsystem as clients of that subsystem. Typically, a modular network of this kind would be located in a small amount of space within a residence, office or factory, and have external connections from the host and client computers to equipment serving local users within a limited range; e.g. up to 200 yards from the box housing the respective network.
Contemporary local area networks (LAN""s), wherein separately housed computers are linked for communication within the confines of a single residence or office, tend to be both inefficient and uneconomical. For instance, xe2x80x9cstand-alonexe2x80x9d personal computers in b; such environments individually contain memory, storage and other resources, that are either unused or infrequently used, that are rarely if ever shared by the other computers, and that are unlikely to ever be used to full capacity before the system needs to be discarded or replaced as xe2x80x9cobsoletexe2x80x9d. Since the cost of each computer in such networks effectively includes costs of such unused resources, as well as a portion of the cost of setting up their network connections, that cost is considerably more than it would need to be if the infrastructure for such a network could be assembled as a single article of manufacture, with all resources and network connections fully integrated into the assembly.
The present invention provides a modular architecture for such networks that overcomes or avoids the foregoing disadvantages associated with operation of xe2x80x9coverly equippedxe2x80x9d computer systems in comparable LAN""s containing stand-alone computers.
A modular computer system architecture conforming to this invention includes a host computer and one or more client computers having at least two of the following attributes: 1) the system is concentrated into a small space; typically within the confines of a small box comparable in size to the housing of a contemporary stand-alone personal computer; 2) the client computers share real-time access to storage and other resources managed by the host computer through a high speed system bus connecting all of the computers in the system; 3) the host computer and resources it manages are mounted on a common integrated circuit substrate; and the client computers are embodied in integrated circuit cards which plug into sockets extending from that substrate; 4) at least one of the client computer cards is xe2x80x9cdisklessxe2x80x9d (i.e. it does not contain a disk drive), and otherwise lacks immediately accessible storage resources, so that the amount of data which it can instantaneously store is a very small fraction of the aggregate amount of data which it must process in real time in order to perform its requisite functions; 5) storage resources managed by the host system include a hierarchy of disk drives and RAM memory, characterized in that information in RAM memory is accessible in a fraction of the time it would take to obtain access to the same information in a disk drive; 6) a portion of the just-mentioned RAM memory is configured to serve as a file cache shared by the client computers; 7) although the client computer cards may have different constructions, they all contain a Modular Network Interface Chip (MNIC) having what is presently considered unique construction and functions, serving to provide uniform connectivity between the other components of the respective card and the system bus; 8) the system bus is operated in several different signaling modes, in one of which the system of host and client computers operates as a self-contained packet routing network enabling the client computers to exchange information packets with each other and/or with the host computer, and in which packets so handled can be orders of magnitude larger than the amount of information which is transferable in a single cycle of bus operation; 9) the system can be connected to networks external to it, but use network signaling processes different from their internal network protocol relative to such external networks; 10) one or more of the client cards has connections external to the system to broadband media (e.g. coaxial cable) enabling respective cards to connect to devices serving remote users (for example, to keyboard, monitor and cursor positioning devices), whereby each such card is potentially capable of serving as an intelligent personal computer in relation to respective remote users, and wherein lengths of such external media can be orders of magnitude greater than the length of the system bus (with the advantage that the speed of communication on the system bus can be used to enable the cards to efficiently share system resources and the lower yet adequate speed of communication over the broadband media can be used to efficiently service the remote users); 11) the client card(s) may contain buffer RAM storage of predetermined minimal capacity, related functionally to the rate of operation of the system bus, whereby communications over that bus are adequate to enable all of the cards to efficiently share access to storage resources managed by the host computer system without significantly sacrificing real-time functionality of respective client systems.
Typically, individual computers in such a concentrated network conform to a standard computer system architecture (for example, the architecture associated with personal computers termed xe2x80x9cIBM Compatiblexe2x80x9d) and use standardized software operating systems for their processing and network communications function (e.g. an Operating System such as Microsoft""s Windows NT(trademark) Verson 4 operating system), although these are by no means restrictive or limiting, and it will be seen, at least in respect to functions relevant to architectural considerations of the present invention, computers using other architectures and other operating system software could readily be adapted to perform equivalent functions.
The system bus also is preferably constructed and utilized as an architecturally standardized system element; e.g. the bus can be configured as a standardized PCI bus conforming to published architectural standards; available e.g. through Internet site www.PCISIG.com. The limited length of this bus (as constrained by the present cluster environment) permit it to be operated at extremely high bit transfer rates, and thereby allow for the sharing of resources by computer systems on the present system board and diskless cards. Thus, data can be passed over this bus at rates that are much greater than rates associated with data transfers over ordinary local area networks (LAN""s).
Other architectural characteristics of systems conforming to this invention are that presently contemplated diskless cards: 1) are removably attached to the system board through socket structures similar to socket structures provided in contemporary personal computer systems for device attachment cards; 2) may have a variety of different functional and hardware organizations, but are interchangeable in respect to their connectivity to the socket structures and the system board resources; 3) contain multiple chip-based components connected by an xe2x80x9cinternalxe2x80x9d system bus representing an extension of the xe2x80x9cexternalxe2x80x9d portion of the system bus that is contained on the system board; 4) one of these components, that is uniformly present on all cards, is the MNIC chip referred to above, which provides standardized connectivity between the external system bus and the internal extension thereof in the card.
Another architectural characteristic of such systems is that certain devices and device adapters located on the system board, which are accessible to the diskless cards only via the system bus shared by all elements of the system, are nevertheless accessible at fast access rates that effectively enable cards to share system board resources while performing real time functions that in personal computer systems require resources dedicated to single computers.
Another characteristic is that the system is designed to accommodate a variety of cards having different processing characteristics and capabilities as computer systems but identical physical characteristics and electrical interchangeability in relation to the aforementioned system board sockets.
Another characteristic is that in systems having their host computer elements adapted to control routing of data packet communications between respective systems and networks external to such systems (e.g. local area networks and public access networks such as the Internet), the foregoing cards are able to exchange data packets directly with each other without requiring routing of such packets to a network hub external to the respective system; thereby reducing the data packet traffic that otherwise would have to be routed between the host system and external network hub.
Another characteristic of such systems is that their diskless cards can be operated as functional equivalents of intelligent personal computer terminals, using connections to broadband media capable of efficiently linking each card to devices remote from the respective cluster. Yet another characteristic is that the cards are economically and efficiently replaceable. Thus, a card technologically limited to supporting activities of a single client could be economically replaced, in the future, with minimal disruption of system utility, as technology advances to a stage wherein a card of comparable size and power consumption is able to support plural clients.
Another characteristic is that a present cluster would cost considerably less and occupy considerably less space than a cluster of separate computers having functionally equivalent computing power.
These and other characteristics, features, and benefits of this invention will be more fully understood and appreciated from the following detailed description.